Impact adapter for transfer of impacts and rotation from an impact rock drilling machine to a drill string

ABSTRACT

Impact adapter for transfer of impacts and rotation from an impact rock drilling machine to a drill string comprising a first end ( 5 ) for connection to a drill string and a second end provided with ridges ( 7 ) and interposed grooves ( 8 ) for transfer of rotation. The grooves ( 8 ) at the end ( 9 ) directed away from the first end ( 5 ) of the impact adapter ( 2 ) are widened in the direction away from the first end ( 5 ).

BACKGROUND OF THE INVENTION

The present invention relates to an impact adapter for transfer ofimpacts and rotation from an impact rock drilling machine to a drillstring.

In previously known impact adapters ridges and grooves at the rear endof the impact adapter are used for transferring torque to a drill stringfrom a driver journalled in the rock drilling machine. Because ofmanufacturing tolerances one has a certain play between the impactadapter and the driver in order to allow the axial movement caused bythe impacts of the rock drilling machine against the impact adapter.This results in the impact adapter coming more or less obliquely in thedriver. This oblique position in combination with the relative axialmovement between the driver and the impact adapter often gives rise tobreakage of one or more of the ridges adjacent the rear end of theimpact adapter.

SUMMARY OF THE INVENTION

The present invention, which is defined in the subsequent claims, aimsat decreasing the problem with ridge breakage by decreasing the surfacepressure between impact adapter and driver. This is achieved by makingthe grooves between the ridges on the impact adapter wider at the rearend of the impact adapter.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is described below with reference to theappended drawing in which

FIG. 1 shows a section through a part of an impact rock drillingmachine.

FIG. 2 shows a part of the impact adapter according to the invention.

FIG. 3 shows a view from the right in FIG. 2.

DISCUSSION OF THE BEST MODES FOR CARRYING OUT THE INVENTION

The rock drilling machine shown in the drawing comprises a machinehousing 1, consisting of several connected parts, in which an impactadapter 2 is displaceably arranged in a driver 4. The driver 4 isrotatable by means of a not shown motor. The driver transfers torque tothe impact adapter 2 via splines 6 comprising ridges 7 and interposedgrooves 8 at a second end of the impact adapter 2. The impact adapter 2is at the front end, a first end, provided with a thread 5 forconnection to a drill string in the usual way. The grooves 8 are at theend 9 directed away from the first end of the impact adapter widenedaway from the first end, which is shown by means of the angle ν.Furthermore the ridges 7 have at the rear end 9 a somewhat smallerradial extension, which is shown by means of the angle μ. Through thisit is achieved that obliqueness between impact adapter and driver givesa lower surface pressure than what is obtained without these widenedgrooves. In the drawing the ridges 7 are formed in the same way at theend directed away from the end 9. The grooves widened towards the endsare suitably produced by feeding the milling tool milling the grooves 8somewhat towards the centre of the impact adapter at the groove ends.

1. Impact adapter for transfer of impacts and rotation from an impactrock drilling machine to a drill string, said impact adapter comprisinga first end section for connection to a drill string and a second endsection provided with ridges and interposed grooves for transfer ofrotation, wherein the grooves at an end of the second end sectiondirected away from the first end section of the impact adapter increasein width in a direction away from the first end section.
 2. Impactadapter according to claim 1, wherein the ridges at the end of thesecond end section directed away from the first end section of theimpact adapter decrease in radial extension in a direction away from thefirst end section.